<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <div id="app">
            <h2>{{fullName}}</h2>
        </div>
        <script src="../../js/vue.js"></script>
        <script>
          const app = new Vue({
                el: '#app',
                data: {
                    firstName: 'Lebron',
                    lastName: 'James'
                },
                computed: {
                    fullName: {
                        set: function (newValue) {
                            const names = newValue.split(' ')
                            this.firstName = names[0]
                            this.lastName = names[1]
                        },
                        get: function () {
                            return this.firstName + ' ' + this.lastName
                        }
                    }
                }
            }) 
        </script>
    </body>
</html>